docs: def get_fallback_resolution(self):
          """Returns the previous fallback resolution
          set by :meth:`set_fallback_resolution`,
          or default fallback resolution if never set.
  
          :returns: ``(x_pixels_per_inch, y_pixels_per_inch)``
  
          """
          ppi = ffi.new('double[2]')
          cairo.cairo_surface_get_fallback_resolution(
              self._pointer, ppi + 0, ppi + 1)
          return tuple(ppi)